/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.oauth2.client.authentication;

import org.springframework.security.authentication.AbstractAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.SpringSecurityCoreVersion;
import org.springframework.security.oauth2.client.OAuth2AuthorizedClient;
import org.springframework.security.oauth2.core.user.OAuth2User;
import org.springframework.util.Assert;

import java.util.Collection;

/**
 * An implementation of an {@link AbstractAuthenticationToken}
 * that represents an OAuth 2.0 {@link Authentication}.
 * <p>
 * The {@link Authentication} associates an {@link OAuth2User} {@code Principal}
 * to the identifier of the {@link #getAuthorizedClientRegistrationId() Authorized Client},
 * which the End-User ({@code Principal}) granted authorization to
 * so that it can access it's protected resources at the UserInfo Endpoint.
 *
 * @author Joe Grandja
 * @see AbstractAuthenticationToken
 * @see OAuth2User
 * @see OAuth2AuthorizedClient
 * @since 5.0
 */
public class OAuth2AuthenticationToken extends AbstractAuthenticationToken {
    private static final long serialVersionUID = SpringSecurityCoreVersion.SERIAL_VERSION_UID;
    private final OAuth2User principal;
    private final String authorizedClientRegistrationId;

    /**
     * Constructs an {@code OAuth2AuthenticationToken} using the provided parameters.
     *
     * @param principal                      the user {@code Principal} registered with the OAuth 2.0 Provider
     * @param authorities                    the authorities granted to the user
     * @param authorizedClientRegistrationId the registration identifier of the {@link OAuth2AuthorizedClient Authorized Client}
     */
    public OAuth2AuthenticationToken(OAuth2User principal, Collection<? extends GrantedAuthority> authorities, String authorizedClientRegistrationId) {
        super(authorities);
        Assert.notNull(principal, "principal cannot be null");
        Assert.hasText(authorizedClientRegistrationId, "authorizedClientRegistrationId cannot be empty");
        this.principal = principal;
        this.authorizedClientRegistrationId = authorizedClientRegistrationId;
        this.setAuthenticated(true);
    }

    @Override
    public OAuth2User getPrincipal() {
        return this.principal;
    }

    @Override
    public Object getCredentials() {
        // Credentials are never exposed (by the Provider) for an OAuth2 User
        return "";
    }

    /**
     * Returns the registration identifier of the {@link OAuth2AuthorizedClient Authorized Client}.
     *
     * @return the registration identifier of the Authorized Client.
     */
    public String getAuthorizedClientRegistrationId() {
        return this.authorizedClientRegistrationId;
    }
}
